Continuous Emission Monitoring, 3rd Edition

APPENDIX AUNITS OF THE STANDARD AND F FACTORS

The form in which emissions standards are expressed can dictate the choice of analyzers or the type of CEM system that is purchased. These forms are given implicitly in the emissions limits that an overall industry or specific facility must meet. For example, for waste incineration, emissions limits are usually expressed in parts per million, corrected for dilution to a specified O₂ or CO₂ concentration. Electric utilities, however, are required to report emissions in terms of mass per heat input (nanograms per joule [ng/J]) or pounds per million British thermal units (lb/mmBtu) and/or in terms of a pollutant mass rate (kilograms per hour, pounds per hour). The form of the emission standard, as well as the types of analyzers necessary to calculate emissions in the units of the standard, will affect the uncertainty of the reported emissions.

For example, using an F_c factor to report emissions in lb/mmBtu (ng/J), in a dilution‐extractive system, the effects of pressure and temperature on the dilution ratio will cancel. However, if an F_d factor is used to report emissions in lb/mmBtu (ng/J), they will not cancel and remedies such as those discussed in Chapter 3 may be necessary.

As another example, reporting pollutant mass emission rates in lbs/hr (kg/hr) or tons/yr (tonnes/yr), the overall uncertainty of the reported data is dependent upon both the pollutant concentration measurement and the flue gas flow measurement. Here, the accuracy ...